# -*- mode: python; -*-
###
#
# (c) 2000-2007 Wijnand Modderman <wijnand at tehmaze dot com>
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#     this list of conditions, and the following disclaimer.
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###

__revision__ = '$Hg: threads.py,v fc566b991f2a 2006/09/11 13:54:15 +0200 $'

# system imports
import thread
import threading
import time

# DDB imports
from ddb.log import log
from ddb.decorator import decorator

# Twisted imports
from twisted.internet.threads import deferToThread
from twisted.python import util
from twisted.python import threadable; 

# Make Twisted ready for threads
threadable.init(1) 

def getattr_(obj, name, default_thunk):
    "Similar to .setdefault in dictionaries."
    try:
        return getattr(obj, name)
    except AttributeError:
        default = default_thunk()
        setattr(obj, name, default)
        return default

# this next functions are meant as decorators to add theadability
# to functions and method calls, use them with care

def delayed(nsec):
    def call(proc, *args, **kw):
        newThread = threading.Timer(nsec, proc, args, kw)
        newThread.start()
        return thread
    return decorator(call)

#threaded = delayed(0) # no-delay decorator
def threaded(proc): 
    """Decorator for deferToThread""" 
    def call(*args, **kwargs): 
        return deferToThread(proc, *args, **kwargs) 
    return call

# The right Twisted way
deferred = deferToThread.__get__

def locked(func, *args, **kw):
    lock = getattr_(func, "lock", threading.Lock)
    lock.acquire()
    try:
        result = func(*args, **kw)
    finally:
        lock.release()
    return result

def blocking(not_avail="Not Available"):
    def call(f, *args, **kw):
        if not hasattr(f, "thread"): # no thread running
            def set_result(): f.result = f(*args, **kw)
            f.thread = threading.Thread(None, set_result)
            f.thread.start()
            return not_avail
        elif f.thread.isAlive():
            return not_avail
        else: # the thread is ended, return the stored result
            del f.thread
            return f.result
    return decorator(call)

# vim:ts=4:sw=4:et:
